Question: At desertusa.com, I found out that cochineal scale is affecting my prickly pear cactus. Although the website described the problem, there was no explanation about how to get rid of it. I used a hose to wash off the scale. Do I need to do something else to save my cactus?
You are right. This is cochineal scale, which is that white, fuzzy stuff on some cactuses. If you crush it between your fingers, it has a very pretty dark red color that oozes from inside the fuzzy stuff. This is not the same scale that is used for red dye but a very close relative, and it still gives off a wonderful color that can be used for dyeing.
The scale insect itself is beneath the fuzzy stuff, where it lies protected and can feed on plant juices. They can infest a cactus quickly and can be difficult to control. They can be a problem on the edible cactuses.
In Mexico, they use hard pesticides such as Sevin to help keep them under control. We usually just use a sweep nozzle on the end of the hose and turn it on all the way. A strong, steady stream of water will wash the scale off the pads.
The problem is that once infested, you will probably have to hose them off once every week or two during the summer. During the winter, it is not as often.
Bob Morris is a professor emeritus in horticulture with the University of Nevada and can be reached at firstname.lastname@example.org. Visit his blog at
Bob Morris is an professor ememeritus in horticulture with the University of Nevada and can be reached at email@example.com. Visit his blog at xtremehorticulture.blogspot.com.